Air quality at Lassen Volcanic National Park

Most visitors expect clean air and clear views in parks. Lassen Volcanic National Park (NP), California, well known for volcanic landforms and interesting geology, lies downwind of the populated Sacramento Valley and areas of agriculture and manufacturing. Air pollutants blown into the park can harm natural and scenic resources such as surface waters, plants, and visibility. The National Park Service works to address air pollution effects at Lassen Volcanic NP, and in parks across the U.S., through science, policy and planning, and by doing our part.

Nitrogen and sulfur

Nitrogen and sulfur compounds deposited from the air may have harmful effects, including acidification, of soils, lakes, ponds, and streams. High elevation lakes and ecosystems at the park are particularly sensitive to nitrogen and sulfur deposition. These systems receive more deposition than lower elevation areas because of greater amounts of snow and rain. Additionally, short growing seasons and shallow soils limit the capacity of soils and plants to buffer or absorb nitrogen and sulfur. Acidification can alter lake and stream diversity and cause loss of sensitive macroinvertebrates and fish (Sullivan et al. 2011a; Sullivan et al. 2011b). Some plants are more sensitive to acidification than others, search for acid-sensitive plant species found at Lassen Volcanic NP.

Volcanic formations at Lassen Volcanic NP, including boiling mud pots and fumaroles, naturally emit sulfur compounds such as sulfur dioxide and hydrogen sulfide. Concentrations of sulfur from volcanic emissions are relatively low and are not known to cause acidification on sensitive resources like high elevation lakes.

Healthy ecosystems can naturally buffer a certain amount of pollution, but as nitrogen and sulfur accumulate, a threshold is passed where the ecosystem is harmed. “Critical load” is a term used to describe the amount of pollution above which harmful changes in sensitive ecosystems occur (Porter 2005). Nitrogen deposition exceeds the critical load for one or more park ecosystems (NPS ARD 2018).

Mercury and toxics

Airborne mercury, and other toxic air contaminants, when deposited are known to harm birds, salamanders, fish and other wildlife, and cause human health concerns. These substances enter the food chain and accumulate in the tissue of organisms causing reduced reproductive success, impaired growth and development, and decreased survival.

Mercury and toxics effects:

Presence of mercury in high elevation lakes in the park (Krabbenhoft et al. 2002).

Concentrations of mercury in fish at three lakes in the park ranged from low to high. Mercury concentrations were lowest in fish from Summit Lake. Fish from Ridge Lake and Horseshoe Lake had concentrations above the mean for all fish across 19 western national parks (Eagles-Smith et al. 2014).

Current-use pesticides (chlorpyrifos, dacthal, endosulfans) are particularly high in fish from parks in the Sierra Nevada (including Lassen Volcanic NP) compared to levels in fish from parks in Alaska and the Cascades (Flanagan Pritz et al 2014).

Low frequency of intersex fish (the presence of both male and female reproductive structures in the same fish) found in the park, which indicates minimal exposure to contaminants (Schreck and Kent 2013).

Ground-level ozone

Ponderosa Pine trees are one of the ozone sensitive species found at Lassen Volcanic NP.

At ground level, ozone is harmful to human health and the environment. Ground-level ozone does not come directly from smokestacks or vehicles, but instead is formed when other pollutants, mainly nitrogen oxides and volatile organic compounds, react in the presence of sunlight. In addition to the local and regional influence of ozone, research indicates global background ozone levels and nearby fires impact ozone exposures at the park (Jaffe et al. 2003; Jaffe et al. 2008).

Over the course of a growing season, ozone can damage plant tissues making it harder for plants to produce and store food. It also weakens plants making them less resistant to disease and insect infestations. Some plants are more sensitive to ozone than others. Assessments conducted in the late 1990’s discovered foliar ozone injury on greater than 25% of the Pinus jeffreyi (Jeffrey pine) and Pinus ponderosa (ponderosa pine) trees sampled in the park (Arbaugh et al. 1998). More recently, the U.S. Forest Service has found ozone injury on trees examined near the park in Lassen County (Campbell et al. 2007). Other plants sensitive to ozone include Populus tremuloides (quaking aspen) and Populus trichocarpa (black cottonwood). Search ozone-sensitive plant species found at Lassen Volcanic NP.

Visibility

Clean, clear air is essential to appreciating the scenic vistas at Lassen Volcanic NP.

Visitors come to Lassen Volcanic NP to enjoy spectacular volcanic landforms and relatively undisturbed natural resources, including forests, lakes, and streams. Park vistas are sometimes obscured by haze, reducing how well and how far people can see. Visibility reducing haze is caused by tiny particles in the air, and these particles can also affect human health. Many of the same pollutants that ultimately fall out as nitrogen and sulfur deposition contribute to this haze. Organic compounds, soot, and dust reduce visibility as well. Significant improvements in park visibility on clearest days have been documented since the 1990’s. However, no significant trends have occurred on haziest days and visibility in the park still needs improvement to reach the Clean Air Act goal of no human caused impairment.

Visibility effects:

Reduction of the average natural visual range from about 165 miles (without pollution) to about 130 miles because of pollution at the park

Reduction of the visual range to below 70 miles on high pollution days

Explore scenic vistas through live webcams at Lassen Volcanic National Park.

Eagles-Smith, C.A., J.J. Willacker, and C.M.Flanagan Pritz. 2014. Mercury in fishes from 21 national parks in the Western United States—Inter and intra-park variation in concentrations and ecological risk: U.S. Geological Survey Open-File Report 2014-1051, 54 p. Available at: http://dx.doi.org/10.3133/ofr20141051.